[5.4] Do not get the profile info for the linked user when no user is linked (joomla#46398)

Author: nordmograph

components/com_contact/src/Model/ContactModel.php

@@ -364,6 +364,10 @@ protected function buildContactExtendedData($contact)
             $contact->articles = null;
         }
 
+        if (empty($contact->user_id)) {
+            return;
+        }
+
         // Get the profile information for the linked user
         $userModel = $this->bootComponent('com_users')->getMVCFactory()
             ->createModel('User', 'Administrator', ['ignore_request' => true]);